Drum Brake Issues

[kmakar]

So the Starfire is running like a champ, serviced the trans, checked and repacked all the wheel bearings and adjusted the shoes for proper pressure, but in drive (going forward) the slightest touch of the brake pedal will send you into the windshield and lock the front brakes up.

I've double verified all components, no leaks, no grease on the shoes or drums, it's got newer bendix brake booster and master cylinder, and the right front wheel cylinder is new. A brake job was performed right before it was parked about 10 years ago.

In reverse it brakes like it should with normal pressure on the pedal, but in drive it's crazy sensitive and locks up the brakes.

Ideas?

 

[Chevelle_Nut]

Are the fronts adjusted too tight? How is the drum surface?

 

[kmakar]

Drum surface looks fine, but they were too tight (had a hard time turning the wheels by hand) and I backed the shoes off just so they are just making contact with drums.

 

[cheveslakr]

might need to bleed the rears again, and make sure they're adjusted correctly. I've had a similar issue that worked itself out once I backed up a dozen times, tapping the breaks....adjusting them a click at a time. If the rears are doing their part, it'll make a big difference in the nose dive.

 

[kmakar]

might need to bleed the rears again, and make sure they're adjusted correctly. I've had a similar issue that worked itself out once I backed up a dozen times, tapping the breaks....adjusting them a click at a time. If the rears are doing their part, it'll make a big difference in the nose dive.

Next plan was to have the drums turned and replace the hoses, then bleed the whole system.

 

[bikeron]

Sure you the correct master cylinder?

 

[kmakar]

Sure you the correct master cylinder?

Yep, confirmed by a number of sources (other than myself). It's a rebuilt unit (both brake booster and Master Cylinder) from Fusick Automotive, and they verified it.

 

[bikeron]

Does it have a separate proportioning/safety valve Dual master cylinder? If so was the proportioning valve cleaned/replaced and checked?

 

[kmakar]

Nope, single bowl master cylinder, no proportioning valve.

 

[bikeron]

Seems very odd...is there residual pressure in the lines? That could indicate a bent line or a master that has valve issues..those old single cylinder masters we're soooo simple though...

 

[kmakar]

Seems very odd...is there residual pressure in the lines? That could indicate a bent line or a master that has valve issues..those old single cylinder masters we're soooo simple though...

I decided to wait until I had all new parts before I pull the drums off. I need to get new bearings and seals, hoses, wheel cylinders, and shoes. Ordering those today, then will take the drums down to be turned.

I'll basically be doing a full brake job in the front and bleeding all the lines and putting in all new fluid.

 

[77cruiser]

Have you driven it enough & done some stops to get the brakes hot?
My 67 Impala that sits most of the time has touchy brakes for a few stops, but I just thought the drums were rusty from sitting.

 

[kmakar]

Have you driven it enough & done some stops to get the brakes hot?
My 67 Impala that sits most of the time has touchy brakes for a few stops, but I just thought the drums were rusty from sitting.

Brakes are too touchy to even drive going forward. I pulled the car off the lift last night to turn it around and almost had some steering wheel for desert.

I'm going to redo the fronts and go from there. Tomorrow I'm going to register it and order the rest of the parts I can't get locally.

 

[Shovelrick]

How old are the front soft (rubber) brake lines?

 

[Alan F]

A collapsed brake line will hold residual pressure. I’d replace all the soft lines. Make sure the brakes are retracting fully. Adjust the shoes again and try to make sure the drag is about the same at every corner. If it continues to do it, I’d retract the front brakes more to see if you can dial in some delay.

 

[kmakar]

How old are the front soft (rubber) brake lines?

The right front looks newer with a newer wheel cylinder, but the rest look original. I'm ordering all new rubber lines today (even in the rear over the axle).

Since I'll be in there, I'll replace the wheel cylinders up front and new shoes, and have the front drums turned just to be completely thorough.

I'll also flush all the brake fluid and put new in. I doubt that was ever done.

 

[kmakar]

A collapsed brake line will hold residual pressure. I’d replace all the soft lines. Make sure the brakes are retracting fully. Adjust the shoes again and try to make sure the drag is about the same at every corner. If it continues to do it, I’d retract the front brakes more to see if you can dial in some delay.

I'd had already retracted the fronts a little and it offered a little more play in the pedal, but still way too sensitive. I'm ordering hoses today (along with most everything else to be complete).

 

[Shovelrick]

About 20 yrs ago I had a 90-1 Chevy 1/2 ton truck that the Front Pass side rubber brake line had collapsed and caused the brake to catch on fire, I pulled in to a gas station/conv. store and grabbed a large cup then filled it with water twice, That was an eye opener LOL

 

[kmakar]

Surprisingly, OReilly's had everything except the wheel cylinders, Napa had nothing. Had to order the wheel cylinders from Fusick Automotive.

 

[Chevelle_Nut]

My Excursions brake lines also collapsed and locked. After I released them I was able to drive it and fortunately I was at home and drove it 25 miles to the shop without touching the brakes.